The human immunodeficiency virus (HIV) often infects and destroys CD4 T cells. These CD4 T cells are one of many kinds of white blood cells that are an important part of the immune system. The most common danger related to the destruction of CD4 T cells is — * A-a decrease in the amount of oxygen being transported to tissues
B-an increase in the risk of high blood pressure
C-a decrease in the flow of blood to vital organs
D-an increase in the threat of diseases caused by microorganisms and viruses

stratosphere: as the altitude increases, the air temperature increases. the stratosphere has a layer of ozone, called the ozone layer. this layer absorbs most of the ultraviolet radiation from sunlight. this results in the stratosphere being warmer.

what school and grade?

b. lithosphere, asthenosphere, mesosphere   is the answer most likely

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.